This invention relates to an idler attaching boss construction and more particularly to an improved arrangement for driving an accessory from an engine.
In engines having one or more overhead camshafts, it is a current practice to employ a timing belt rather than a timing chain for driving the camshaft. There are a number of advantages to the use of timing belts over timing chains, which advantages are well known. When a timing belt rather than a timing chain is employed, the belt is positioned externally of the outer walls of the engine, normally at the front of the engine. In order to protect the belt, it is the practice to attach some form of belt cover to the front wall of the engine so as to enclose at least partially the belt and the various sprockets or pulleys which drive or are driven by it. These belt covers are normally formed from a lightweight material, such as a molded plastic.
In addition to driving the camshaft or camshafts from the engine output shafts, it is also the practice to drive a plurality of accessories. These accessory drive arrangements are normally positioned outside of the belt cover and may power such accessories as power steering pumps, air conditioning compressors, alternators or the like. When the camshaft drive is enclosed by a lightweight belt cover, then it is necessary to mount the accessories and the idler pulleys therefore in a rigid manner from the front of the engine. However, this means, in conventional practice, that the drive pulleys and idler pulleys for the accessories must all have their rotational axes disposed outside of the periphery of the belt cover. This gives rise to long belt flights and the problems attendant thereto.
It is, therefore, a principal object of this invention to provide an improved idler attaching boss construction that permits the driving of an accessory or an idler pulley for an accessory that has an axis of rotation that is disposed within the peripheral confines of a belt cover, but which nevertheless is rigidly supported.
It is a further object of this invention to provide an improved arrangement for driving accessories from an engine having one or more belt driven camshafts.